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# This file is part of meas_astrom. 

# 

# Developed for the LSST Data Management System. 

# This product includes software developed by the LSST Project 

# (https://www.lsst.org). 

# See the COPYRIGHT file at the top-level directory of this distribution 

# for details of code ownership. 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 3 of the License, or 

# (at your option) any later version. 

# 

# This program is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

# GNU General Public License for more details. 

# 

# You should have received a copy of the GNU General Public License 

# along with this program. If not, see <https://www.gnu.org/licenses/>. 

 

__all__ = ["denormalizeMatches"] 

 

import lsst.afw.table as afwTable 

 

 

def denormalizeMatches(matches, matchMeta=None): 

"""Generate a denormalized Catalog of matches 

 

This is intended for writing matches in a convenient way. 

Normally we write matches in a 'normalized' form: recording only the join 

table (reference ID, source ID) to minimise space (the reference and source 

catalogs should both be available separately, so the only extra information 

we need is how to join them). However, using that can be a pain, since it 

requires reading each catalog and doing the join. 

 

This function generates a Catalog containing all the information in the 

matches. The reference catalog entries are in columns with "ref_" 

prepended, while the source catalog entries are in columns with "src_" 

prepended (including any alias mappings). The distance between the 

matches is in a column named "distance". 

 

Parameters 

---------- 

matches : `list` of `lsst.afw.table.ReferenceMatch` 

List of matches between reference catalog and source catalog. 

matchMeta : `lsst.daf.base.PropertyList` 

Matching metadata to write in catalog. 

 

Returns 

------- 

catalog : `lsst.afw.table.BaseCatalog` 

Catalog containing matchlist entries. 

 

See also 

-------- 

`lsst.afw.table.packMatches` 

""" 

if len(matches) == 0: 

raise RuntimeError("No matches provided.") 

 

refSchema = matches[0].first.getSchema() 

srcSchema = matches[0].second.getSchema() 

 

refMapper, srcMapper = afwTable.SchemaMapper.join([refSchema, srcSchema], ["ref_", "src_"]) 

schema = refMapper.editOutputSchema() 

 

schema = afwTable.catalogMatches.copyAliasMapWithPrefix(srcSchema, schema, prefix="src_") 

schema = afwTable.catalogMatches.copyAliasMapWithPrefix(refSchema, schema, prefix="ref_") 

 

distKey = schema.addField("distance", type=float, doc="Distance between ref and src") 

 

catalog = afwTable.BaseCatalog(schema) 

catalog.reserve(len(matches)) 

for mm in matches: 

row = catalog.addNew() 

row.assign(mm.first, refMapper) 

row.assign(mm.second, srcMapper) 

row.set(distKey, mm.distance) 

 

if matchMeta is not None: 

catalog.getTable().setMetadata(matchMeta) 

 

return catalog